Time Travel ... it throws me for a loop every time. There were times I thought I had a handle on it, then wham, I was lost. It has to be done well, to keep the story moving and not lose the reader. This one toed the line for me, but I didn't get so totally lost that I wasn't able to follow along. I did however have to re-read sections before I got it. But I can be a little slow sometimes, especially at midnight when I was staying up to finish it. Because I needed to know what was going to happen!Kate has a ... complicated family history. She is roughly 300 years older than her grandmother. Who she has to learn to trust, and it is up to her to not only save her family from never existing, but possibly even the world from a crazy religious cult from taking over. No pressure.I have to admit there were a few places I had to suspend my own logic and just believe the story. A science background sometimes makes it hard to read about science. Especially future science. With things that are not possible. (Side note - I know time travel technically isn't possible, but that is the one thing I knew going in I was going to have to suspend belief for) This is one of those, "They explain why and even though it is outrageous I just have to believe it possible," stories. So if you have a hard time suspending belief or following multiple time line possibilities, this may be one you want to skip.However, if you like pondering the what-ifs, and the if-onlys, then you will love this. How many of us could go back in time and not change things? Save a life? Stop a war? I personally would try to prevent some animal extinctions. But what would those changes affect in then current time? Would you even be born? O_OAnd while there is definitely more story to be told, there is not a cliffhanger ending. Thank the YA gods! If you do read this, I am curious to know what your thoughts are. Please come back and let me know! The discussion we could have ... oh buddy. :-)